The present invention relates to small-scale, rotatable antennas used with restricted profile devices in the computer and communications industry. More particularly, the present invention relates to a method and apparatus for reliably connecting to an antenna radiator which pivots on a hinge or similar mechanism and for connecting to associated ground plane elements.
Some standards in the electrical connector industry have been created by government regulation such as the Federal Communications Commission""s Title 47, xc2xa768.500, otherwise denoted xe2x80x9cSubpart Fxe2x80x94Connectorsxe2x80x9d (Subpart F). Subpart F is incorporated herein by reference. Subpart F contains detailed specifications for xe2x80x9cminiaturexe2x80x9d connectors used in the communications industry. Included in this specification are the xe2x80x9cMiniature 6-position plug and jackxe2x80x9d and the xe2x80x9cMiniature 8-position plug and jack.xe2x80x9d These connectors, commonly known as the RJ-11 connector and the RJ-45 connectors, respectively, are ubiquitous throughout the industry.
The miniature 6-position connector or RJ-11 has emerged as the industry standard connector for telephone lines. RJ-11 plugs and jacks are used on almost all telephone sets for connection to the phone system and consequently are used for standard modem connections which also use these telephone lines. Although most telephone companies use only 4 or 2 of the available positions on the connector, the 6-position connector is the standard.
The miniature 8-position connector or RJ-45 has become an industry standard connector for computer networks. It is used for inter-connectivity between network adapter cards, hubs, routers, switches and other network hardware.
These connectors have been the industry standard for many years and are likely to remain so in the future for telephones, desktop computer modems and network adapters, and other substantially stationary communications equipment. However, hardware technology and the xe2x80x9cminiaturizationxe2x80x9d of components has progressed to the point that the standard, xe2x80x9cminiaturexe2x80x9d RJ connectors have a larger cross-section than the thickness of the hardware to which they connect.
An example of these smaller, thin profile hardware configurations is the PC Card Standard promulgated by the Personal Computer Memory Card International Association (PCMCIA). The PCMCIA PC Card standard identifies three primary card type designations: Type I, II and III. These type designations correspond to physical dimension restrictions or xe2x80x9cform factorsxe2x80x9d of 85.6 mm (length)xc3x9754.0 mm (width) and thicknesses of 3.3 mm, 5.0 mm and 10.5 mm respectively. These thin profile expansion cards are used to expand the functionality of computers and related products by adding circuitry contained on the card to the host device. Host devices, such as laptop computers, contain expansion slots which receive the expansion cards and provide electrical connections thereto. Modems and network adapters are often constructed in PC Card standard form factor.
As a consequence of hardware miniaturization in the face of a nearly worldwide RJ connector standard, hardware manufacturers have developed myriad proprietary hardware connection standards and an assortment of connectors and adapters that allow the RJ plugs to be connected to thin profile hardware.
One elegant and convenient connector which allows connection of the standard RJ type plug with thin profile hardware is the XJACK(copyright) produced by 3Com Corporation, Salt Lake City, Utah. The XJACK(copyright), shown generally in FIG. 1, is a thin profile connector designed to be contained within hardware such as PC Card standard compliant devices. The XJACK(copyright) comprises a thin body 1 with an aperture 3 therein for receiving a standard RJ connector plug 5 such as a miniature 6-pin plug, a miniature 8-pin plug or some other connector. Jack conductors 7 contact plug conductors 9 just as a conventional RJ jack connects. The XJACK(copyright) may be retractable within the device or be detachable therefrom. Commonly used XJACK(copyright) connectors retract in and out of a device by sliding along a track. A spring is often used to bias the XJACK(copyright) connector such that it pops out of its retracted state and remains extended during use.
Wireless communication devices are now becoming commonplace in the electronics industry. Wireless networking of portable computers and associated devices is now replacing a large segment of the networking market. Wireless communication devices including wireless networking adapters, hubs and other equipment utilize radio transmitters and receivers to transmit data signals from one device or node to another. These radio transmitters and receivers must utilize a specific frequency band and protocol to accomplish this task. Since these wireless networks and communications areas may often overlap, standards, protocols and privacy protection are necessary. One current standard in the industry has been established by the Institute of Electrical and Electronics Engineers, Inc. (IEEE) and is known as IEEE 802.11. This standard comprises communications standards, protocol and equipment specifications for wireless communication equipment including privacy and encryption provisions.
Another emerging standard in wireless communications and networking, known as Bluetooth(copyright), is being established by a collaborative group of communications and computing companies. Devices incorporating Bluetooth(copyright) technology will utilize a micro-chip transceiver for communications between devices. Bluetooth(copyright) devices will transmit in the previously unused 2.4 GHz range. Bluetooth(copyright) technology promises to be a viable and economical networking solution for interconnection of cell phones, computers, printers, modems, computer peripherals, fax machines and other communications and computing devices. The size of the Bluetooth(copyright) transceiver will make it usable in devices as small as palm computers and cell phones.
Antennas are well known for enabling and improving transmission to radio receivers and from radio transmitters. Antennas can dramatically increase the range of radio transceivers, however most antenna designs function best when protruding from their host device. In small electronic devices protruding antennas are often vulnerable to breakage as the devices are often stowed in purses, pockets, backpacks and other areas where neglect can occur. A retractable antenna is more convenient and durable and occupies less space when retracted.
Because many antennas perform better when oriented in a vertical position, they often must be able to rotate from a horizontal xe2x80x9cstoragexe2x80x9d position to an xe2x80x9cin-usexe2x80x9d vertical position. For compactness, they may then re-rotate to horizontal before retraction into a host device. This function is often achieved through a hinge or similar mechanism. While this rotation function is easily achieved with known methods and apparatus for the physical antenna itself, it presents a challenge to those designing the electrical connection to the movable or rotatable antenna.
Connection methods are known whereby a contact on one side of a hinge rests on a conductive portion of the other side of the hinge thereby effectuating electrical contact therebetween. However, this xe2x80x9cwiperxe2x80x9d technology presents a problem with antenna connections because the impedance of the connection varies considerably as friction, oxidation and corrosion affect the contact between the two materials. This variance in impedance can adversely affect the performance of a low power antenna such as those used with short-range wireless devices.
Conventional xe2x80x9cflexxe2x80x9d cables are also known for connection to a rotatable or movable extension or device. However, these connectors often require a minimum bend radius that precludes their use in more compact movable parts.
The present invention relates to small-scale rotatable antennas used in conjunction with electronic devices or extensions thereof. These hinged or otherwise rotatable antennas may connect directly to a small electronic host device or to a retractable extension thereon, however the electrical connection must be able to flex or rotate with the movement of the antenna. These antennas may also function in conjunction with ground plane elements.
When a coaxial connection cable is used to connect an antenna/ground plane combination to a transceiver, the ground plane element is connected to the shielding conductors and the central coaxial wire is connected to the antenna radiator or the central coaxial wire becomes the radiator itself. If the antenna radiator is rotatable, the coaxial cable connection or conductors in the coaxial cable themselves must be able to flex with the rotation of the radiator. The conductors in the cable shielding and the radiator conductor must be able to deform elastically as the antenna is deployed and stowed over the life of the device. If either the shielding or the radiator conductor fails, the antenna will not function properly and device performance will be compromised. Therefore, a reliable method and apparatus for connection to the antenna is desirable.
Embodiments of the present invention comprise an antenna housing which is pivotally connected to an electronic device or extension thereof. The antenna housing pivots from a substantially vertical xe2x80x9cusablexe2x80x9d position to a substantially horizontal xe2x80x9cstoragexe2x80x9d position. As the antenna housing is moved from the usable position to the storage position it pivots along a hinge axis. In some embodiments of the present invention, at one end of this axis, a conductor enters the antenna housing and connects to or transitions into an antenna radiator contained in the housing. In some other embodiments, the coaxial cable may enter the antenna housing from the side of the hinge and substantially perpendicular to the axis of rotation of the hinge.
A ground plane element is located adjacently and preferably centrally to an initial segment of the antenna radiator. This ground plane element may be integral to the host device or an extension thereof or may be on a surface thereof. In preferred embodiments of the present invention, the ground plane element may be a conductive material which is insert molded, cold or heat staked, or adhesively bonded to the extension. For example, and not by way of limitation, conductive mesh molded into a plastic housing or extension, a conductive foil element sandwiched into a housing or extension, or a conductive plate heat-staked to a device or extension.
The ground plane element will preferably be exposed along a channel in the device housing or extension in which coaxial cable will pass as it connects to the antenna radiator. As the cable passes through the channel with an exposed ground plane element the cable shielding is bared so that it will contact and electrically connect with the ground plane element.
Contact between the cable shielding and the ground plane element is enhanced by the cross-sectional shape of the channel and a compression-fit retainer block, plate or other element which biases the cable against the ground plane element. The cross-sectional shape of the channel and the size of the channel are set so as to achieve a mild compression of the cable in the channel when the retainer block, plate or other element is assembled into place. This compression maintains a positive connection between the ground plane elements and the cable shielding during the life of the device. Preferred lateral cross-sectional channel shapes include, but are not limited to a semi-circle, a v-shaped cross-section and a rounded v-shape.
This connection may also be enhanced by varying the longitudinal shape of the cable channel. Positive results have been obtained with a channel which tapers to a narrow xe2x80x9cneckxe2x80x9d near the center of the channel thereby forcing increased compression and deformation of the cable at that point and allowing the ends of the cable to flex more freely.
The retainer block, plate or other retaining element of the present invention may be constructed to have a snap-fit assembly, a heat-staked assembly, bonded assembly or some other assembly as is necessary for optimal economy.
Certain embodiments of the present invention may also comprise a xe2x80x9cmodified monopolexe2x80x9d antenna. The modified monopole antenna has a radiating element which typically protrudes substantially vertically from a ground plane element and curves away from device circuitry then curves back toward the vertical forming a shape that may be angular or curved. The shape has been found to improve antenna performance from that of a strictly vertical antenna located at the edge of a ground plane. The shape allows the antenna to protrude from near the center of the ground plane element and then curve away from device circuitry which may produce interference. The antenna typically terminates in a substantially vertical direction.
Accordingly, it is an object of some embodiments of the present invention to provide a rotatable antenna with a secure electrical connection to a host device.
It is also an object of some embodiments of the present invention to provide a secure connection to an antenna ground plane element.
These and other objects and features of the present invention will become more fully apparent from the following, description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.